This application claims the priority of German patent application 100 39 090.0, filed 10 Aug. 2000 (PCT International Application PCT/EP01/09115, filed 7 Aug. 2001), the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electronic starter and steering locking device for a motor vehicle.
Particularly in automobiles, it is customary to provide a steering locking unit that performs an immobilizer function by holding the steering lock (or an equivalent vehicle steering element) locked against activation until the user of the vehicle has confirmed his authorization to drive the vehicle by means of a corresponding authorization arrangement (for example a mechanical or electronic key). The steering locking unit is coupled to the vehicle starter unit in such a way that it is ensured that it remains in its unlocked state when the engine starts.
In a device of this type, the vehicle starter unit comprises a mechanical ignition key/ignition lock system in which the ignition lock can customarily be rotated between (for example four) different positions by means of a key which provides authorization to drive. The steering locking unit comprises a locking control unit and an actuating unit which is actuated by it, with the steering locking unit being fed via a voltage supply line. When voltage is not applied to it, the steering locking unit is in the unlocked state from which it can be switched into its locked state by applying a voltage. The supply line is routed via the rotatable ignition lock, which thus functions as a looped-in mechanical break contact, i.e., interrupter switching element. The switching element keeps the supply line closed as long as the ignition lock has not yet been turned out of its home position (in which the key can be inserted and removed) by an angle which exceeds a predefinable threshold value; and the steering locking unit is correspondingly in its locked state. If the ignition lock is turned beyond the angular threshold value it interrupts the supply line, ensuring that the steering locking unit is in its unlocked state when the vehicle engine subsequently starts.
German Patent Document DE 196 34 627 C1 discloses an arrangement for coupling a steering wheel locking unit to an electronic immobilizer in which the steering wheel locking unit has a bolt as an actuating element. Movement of the bolt between an unlocked position and a locked position is blocked by means of a blocking device if the electronic immobilizer is primed. When the electronic immobilizer is disabled, the blocking device releases the bolt which can then be moved into its unlocked position, for example by the head of a vehicle key, by a separate transponder or a Bowden cable. Alternatively, the bolt can be activated by turning an ignition key which is plugged into an ignition lock as is known, for example, from German Patent Documents DE 44 34 587 A1 and DE 44 46 613 A1.
In modern automobiles, purely electronic ignition starter switch units without a mechanical ignition key/ignition lock system are increasingly being used as the vehicle starter unit. This includes in particular, systems without active key activation; i.e., what are referred to as keyless-go systems in which a locking system and an electronic immobilizer are controlled via wire-free communication by means of an authorization element, for example in the form of a chip card. For this purpose the latter needs merely be carried by the user, without the need for further action on his or her part.
German Patent Document DE 199 16 966.7 which is not prior art, discloses an electronic starter and steering locking device of the type mentioned above which is also suitable for such keyless-go systems. It includes status interrogation and starting blocking means which couple the steering locking unit to an ignition starter switch unit, interrogate the locked state of the steering locking unit and enable starting of the vehicle engine only if the interrogation reveals that the steering locking unit is in its unlocked state. In one advantageous embodiment, the steering locking unit has an actuating unit which actuates a locking control unit and an ignition starter control. The latter has a data communications link to the locking control unit, and is arranged in the ignition starter switch unit.
The voltage supply for both the locking control unit and the actuating unit is provided via a supply line that is connected to the vehicle's electrical supply independently of the operating state of the ignition starter switch unit, or is routed via the ignition starter switch unit in such a way that the steering locking unit is fed with either the full power of the vehicle's electrical system or a reduced power of the vehicle's electrical system. The steering locking unit can be switched over as a function of its operating state and in particular of the position of a mechanical ignition lock which is provided in it.
The reduced power is achieved by means of a current limiting function and is selected such that, although it is sufficient to operate the locking control unit, it is no longer sufficient to activate the actuating motor of the locking actuating unit. As a result, the locking control unit can be continuously interrogated by the ignition starter control unit with respect to the locked state, even in situations when the ignition is switched on.
In the driving mode, the steering locking unit should be prevented from inadvertently being placed in its locked state. One measure to ensure satisfaction of this safety measure in vehicles with automatic transmission is to conduct the voltage supply for the steering locking unit via a breaker contact which is assigned to the automatic transmission shift lever. Thus, the voltage supply is surely interrupted, even if the shift lever is not in the parked position “P”.
European Patent Document EP 0 733 524 A1 discloses an electronic anti-theft device for a motor vehicle in which the starter is prevented from being supplied with electrical energy if the activation motor of a blocking device (anti-theft protection) of the anti-theft protection device has not reached an unlocking position. The activation motor of the blocking device is connected to a power source via a key switch when there is no key in an anti-theft switch. When the key is inserted into the key switch, the activation motor is connected to an unlocking contact which is assigned to a control switch. The unlocking contact only interacts simultaneously with the contact of the starter. The locking or unlocked state of the anti-theft protection is sensed by means of the status-determining switch.
One object of the invention is to provide an electronic starter and steering locking device of the type mentioned above which, on the one hand, reliably prevents the steering locking unit from being placed in the locked state in the driving mode, and on the other hand permits the state of the steering locking unit to be interrogated in order to start the vehicle independently of the position of a drive train transmission shift lever.
This and other objects and advantages are achieved by the electronic starter and steering locking device according to the invention, in which the voltage supply is characteristically provided in different ways for the locking control unit on the one hand and the locking actuating unit on the other. Specifically it is provided such that the locking control unit is permanently connected to the voltage supply, independently of the driving state of the vehicle (and thus in particular independently of the operating state of the vehicle starter unit and of the position of a drive train transmission shift lever), while the locking actuating unit is connected to the voltage supply via interrupter switching means. The latter can be switched over as a function of the operating state of the vehicle starter unit and/or of the switched position of the drive train transmission shift lever.
Separating the supply to the respective components of the steering locking unit in two in this way ensures, on the one hand, that the locking control unit is permanently operationally capable and that it is therefore always possible to communicate with it (for example, to interrogate the locked state of the steering locking unit). On the other hand, it is also ensured that, in specific driving operating states, the locking actuating unit cannot be inadvertently actuated and thus be placed in the locked state. As a result, it is, for example, advantageously ensured that, in a vehicle with automatic transmission, it remains possible to start the engine in the shift lever position “N”, even if the voltage supply of the locking actuating unit is interrupted in this shift lever position. Starting of the engine is made dependent on a successful interrogation of the locked state of the steering locking unit by the vehicle starter unit.
Furthermore, the device contains as interrupter switching means a switching element which is assigned to the vehicle starter unit and whose switched position is thus dependent on the operating state of the vehicle starter unit. In series with the latter is a switching element whose switched state is dependent on the position of an automatic transmission shift lever. As a result, the supply voltage of the locking actuating unit is interrupted both in certain operating states of the vehicle starter unit and in certain operating states of the automatic transmission shift lever, so that the steering lock system is thus kept in the unlocked state.
In another embodiment of the invention, the vehicle starter unit contains a vehicle starter control unit which has a data communications link to the locking control unit. As the link is permanently activated (i.e., independently of the driving state), the communications link to the vehicle starter control unit is also maintained continuously.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.